Patent document CH-B-675 339 has already proposed a wrist-watch the caseband of which can be constituted of any non-metallic material, natural or synthetic. Such caseband exhibits a cylindrical housing in which a case sheltering a movement is secured by means of a toroidal elastic packing engaged on the one hand in an annular groove of the cylindrical housing and, on the other hand, in a peripheral groove of the case. The caseband is provided with a metallic armature to which a bracelet is brought for attachment.
The summary construction described hereinabove does not suit an ultra-thin watch, that is to say, a watch the thickness of which does not exceed approximately 4 millimeters. In effect, it will be understood that recourse to an independent case sheltering the entire movement, back cover and crystal included, such case having additionally to be secured to the caseband by a toroidal elastic packing, leads to a piece which is necessarily thick. On the other hand, the metallic armature proposed has as a purpose only to withstand the substantial forces exerted on the watch by the various tractions exerted by the bracelet and can in no way at the same time play the role of a baseplate, as such is the case in the present invention which is to be described hereinbelow.
It is not indicated in the document cited hereinabove whether the described arrangement is suitable for a case formed of plastic material into which the metallic element would be sunk by overmoulding of said material. One may nevertheless consider it so if reference is had for example to patent documents CH-B-580 294 and FR-A-1 363 424, which both describe a reinforcing metallic insert sunk into a case injected in plastic material. In these documents, however, the insert in question is not used to retain a bracelet any more than it is used to serve as a base plate for a movement.